The decriminalization of medicinal marijuana in numerous states has increased the demand for research on how marijuana affects patients. Unfortunately, there is currently no standard means for assessing the cognitive and neurophysiological changes resulting from marijuana smoking. Accordingly, we propose to develop a self-contained device, the NICE (Neurocognitive Index of Cannabis Effects) system, to objectively and efficiently assess marijuana-related changes in cognitive brain function. In Phase I we collected data from ten recreational marijuana users before and after the smoked marijuana cigarettes containing an active or a placebo dose of THC. After smoking marijuana subjects were less accurate in a test of intermediate-term memory, and responses in a sustained attention/working memory task were slower. Marijuana produced large concomitant changes in task-related EEG and event-related potentials. Multivariate combinations of performance and neurophysiological measures readily tracked the neurocognitive changes following marijuana smoking. The Phase I project also contributed to the ongoing design of a compact and highly automated testing and analysis system. In Phase II we propose to extend and further validate our procedures for classifying marijuana's effects on an individual basis using a larger database, fully implement a prototype system, and subject it to independent evaluation studies. PROPOSED COMMERCIAL APPLICATION: Not Available